Low lift attachment for hydraulic jacks



May 10, 1949. c. L. THOMPSON LOW LIFT ATTACHMENT FOR HYDRAULIC JACKS Filed March 11, 1946 Patented May 10, 1949 as ear-Eur DEF-ICE.

LOW LIFT- ATTAUHMENTLFORHYDRAUIJIC' JACKS Charles LI. Thompsongflakland', Calif.

'- lapplication Mar-ch 11, 1946; Serial No'. 6531523 (Cl."254-i-.--133) 2 Claims This invention; aalowz-lift iattachnrent-iorijacks isparticularlyidesigned.for useful-connection with hydraulicrja'ck's thoughit may berused with other types :of L-ja'cksi which have' no low-liit step;

. .aI-Iydraulic. jacksare not conventionally providedi with a l'owl-liftstep;v having. only :the. con? ventional. lifts he'ad axially align'edwith .the'bylinder, ::and there are-innumerablecases where the jack cannot be used "because. the jack isztoo high to be placed underrtheobject to be lifted. Under such foonditions: it" is; necessarYrto-revertto some type of mechanical jack having .'a-1'oweliftstep thusdncre'asingrthe:iefiorti'and the time necessary torliftthe oblect.

This. invention :provides a: low-lift 'attaclnnent which can be applied to any hydraulici-jaclo :and requires no '7securing. means for retention z'onnthe jack. :It operates smoothly and can :be: arranged to I lift from iS'LlbStflIltaiillY" floor or mpport level, and canberrmorinted at WiIlitO: :lift from va: point at any desired. angle to the pump: handle :or'other operating meansyso that: the -ha;ndle::or- :otherl'operatingmmeans -can-be: operated' from thel-most convenient and accessiblexposition.v The: attach+ merit sis .ialpplied simply: byr hangingi it. over *the head 'of the 'jack. .Ilr. makesathe jackl adjustable for lifting r from any desired elevation 1 belowflthe head.

The' objects and advantages of the invention areasfollows First,'.i;o'-1provide=alow-lift attachment'forhydraulic'rjackszso that the jack carrbe". madewto lift. from any desired-level below the "lowered po sition of the 'h'e'ad'ofithe-jackplunger.

Second; 'to provideian "attachment sasroutlined which requires? no: manually operable securing means for fattachmentrto: theija'ckgeone .WhiChiis simply placed in: position and removedifat will.

Third; 'to I provideen attachment as outlined with non-cutting positive guiding means for retaining the low-Jift-stepin alignment under load.

Fourth, to provide an attachment as outlined with an adjustable and removable low-lift step, so that the low-lift step can be arranged to lift from the most desirable level; and replaced by a step of. difierent form for specific lifting 'conditionssat will.

Fifth, to provide an auxiliary .base for the jack when the attachment is used for "lifting exceptionally heavy objects, and which auxiliary-base is ra-pplicable or removablez'merely by placing it under the base with no securingmeans required.

Sixth, to provide an attachment as outlined which is of the utmost simplicity in construc- ,2 tion and'iopera-tion and having 'an absolute minimumnuinber of parts.

In describing the invention referencewill'be made "to the accompanying-drawings, 'inwhich:

Fig; l is a side'elev'ation of the inventionshown applied'to a hydraulic jack.

*Fig. 2 is atop-plan view of thejack plunger and cylinder and shows the drop' memberin section to illustrate the function" and operation *of the concave bearing roller and its-cooperation with theeylin'der wall.

-=*F'ig5 3- is aside elevation ofthe" adjustable step and' shows' 'the rack an-done side of the slot.

Fig? 4 is a tran'sverse section throughthe' drop member and shows the tensionmeinber and-cross+ member in position within the slot.

l ig. 5 is a-=modifioation showingifragmentarily the simplestform of the invention-in which the step is non-adjustable.

The invention-is applicable to any type of hydraiulic; pneumaticor mechanical jack having a body'of *oyl-inder' l0 and a'screw, ratchetorpllmger I I terminating in a pivotal-head 'IZ'and having operating means such as the pump l3 and pumpoperating lever l t'for actuating the, jack; and consists ofahead member l5' which is' provided with a depending flange [6 to encompass the head I2 =ai1dhook over the transverse-thrust s'i'detas indicatedat 16, and having a drop member 'I I which-"in conjunction with the head member is of an invert'ed L' shape, the'drop member. having mounted-inits lower end 18 aconcave roller [9 asiridicated at 20; the concavity conforming "as closely as possible totheperiphery of 'thezc'ylinder but nefera'hly having a slightly lesser radiussoithat-the outer edges "of theroller ride on thepylinder tobetter'maintain alignment of. the attachment.

i A low-lift" step" is provided for the attachment, andin'its simplest form'consists "of a step 2| which is formed. integral with the;lower. end- 0f the drop member "TI 1 .as' indicated iri'FigI ,.5,'.and having ribs 22 between which'the ro1lerJ9is sup.- ported 'as'ir'idicated at 23. "This type is devoid of adjustment and therefore is limited to the degreeof 'lift in proportion .to the degree .to which the "plunger must be raised before. contact is made between the object-and. thestep.

""Ifhe preferred form of the invention has an ad: justabletstep asrindicatectinfiigs. 1, 3 and:.,4,.in which aslot' 24 i'sformed.centrallyt'oflthez Lvviidth oi the drop member/ll. andilanked externally by, suitable support means such .as ..the .rack IP25; andlnternally'by'thrust surfaces 26' flanked by the ribs 21.

The step 28 has depending ribs 29 which terminate in teeth 30 complementary to those formed on the front face of the drop member, and are formed only on the lower portion of the ribs. A tension member 3! is cylindrical in cross-section and terminates in a cross-pin 32, the member 3| being slidable and rotatable in the slot 24, and the cross-pin 32 riding on the surfaces 26, the member 3! being formed angularly upward as is clearly illustrated in Fig. 3 and is formed integral with the step and cross-pin.

A base extension 33 terminates at one end in a hook 34 to fit over the edge of the foot 35 on the jack, and is made suificiently long to take the vertical thrust on the step and thus prevent tipping of the jack. Under ordinary conditions this extension will not be needed, but it is a necessary adjunct in case of very heavy objects or when the object is apt to move under lateral thrust or which is in an unstable condition.

For use, the attachment is simply hung over the head of the plunger as indicated in Fig. 1. The depending flange [6 forms a recess and holding means for the head I2. The roller [9 extends partially about the periphery of the cylinder as indicated in Fig. 2 to maintain alignment of the attachment with the axis of the jack and this roller simultaneously provides substantially frictionless travel of the attachment as the jack is operated.

If the solid step shown in Fig. is used, the jack is adjusted up until the step cooperates with the object to be lifted, the degree of lift being equal to the difference between the lift required to bring the step up to the object and the total lift of the jack.

The adjustable step illustrated in Figs. 1, 3 and is replaceable and interchangeable, so that the most desirable type of step can be used at will, and assembly is easily and quickly effected. For assembly, the step is turned sideways, the pin 32 is passed through the slot, then the step is turned to its operative position which causes the pin to span the slot and bear on the surfaces 26, this assembly being accomplished by having the strain member 3! at right angles to the drop member When the attachment is in use, the step is raised at its outer end which moves the teeth 30 on the step ribs out of engagement with the rack 25 on the drop member. The step can then be raised to the proper height to engage the underside of the object (the jack being adjusted to its lowest limit), then lowered so that the teeth again engage. With this arrangement the object can be raised to a height equal to substantially the total travel of the jack plunger, or lowered to the same degree, and can be made to lift from substantially floor level. Thus the jack is capable of lifting through about twice the distance of which it is capable alone.

If the object is unstable, the foot extension 33 is placed on the bottom of the jack to prevent tipping, the load then being taken by the extension 36.

I claim:

1. A low-lift attachment for hydraulic jacks having a cylinder and a plunger and a pivotal head for said plunger, comprising; a cap memher to fit over and engage said pivotal head and having a drop member at one end extending down substantially to the foot of the jack when the plunger is retracted and having a bearing at its lower end for cooperation with the side of the cylinder; said drop member consisting of two spaced members forming a vertical slot therebetween and a rack formed on the front face of each member; said step having a tension member passing through said slot and terminating in a cross-member for cooperation with the back wall of said spaced members on the respective sides of the slot, and cooperative teeth formed on the rearwardportion'of said step for engagement with said rack; said tension member being cylindrical in cross-section and being formed angularly upward and backward to provide for removal, replacement, or adjustment of the step at will, said step having teeth formed only in spaced relation below the level of the top of the step whereby upward swing of the step about the tension member axis moves the teeth out of engagement with the rack, and turning of the step about the axis of the tension member frees the cross-member for removal through the slot.

2. In a low-lift attachment having a cap portion to engage over the head of a hydraulic jack; a pair of spaced drop members forming a slot therebetween and with the upper ends integral with said cap portion and having a concave roller and a shaft therefor mounted at the lower ends to cooperate with the body of the jack, said shaft forming a tie between said lower ends; rack teeth formed on the front face of each of said drop members; a step having a back wall with rack teeth formed on the lower portion on each side for cooperation with the rack teeth on said drop members, and a tension member projecting diagonally upward centrally from the upper end of said back wall and terminating in a cross member to cooperate with the back walls of the drop members; whereby tilting of the forward end of the step under load is eliminated, and lifting the forward end of the step frees the step from said drop members for adjustment at will, and lifting the forward end of the step followed by rotating the step through a quarter turn frees the cross member to pass through the slot for removal and replacement of steps at will; said tension member having a cross-section fitting closely within the slot to maintain stability and being cylindrical in cross-section to permit rotation for removal and replacement of the step, said drop members being complementarily stepped inwardly from the back wall thereof with the cross member cylindrical in cross-section and fitting slidably between the side walls of the complementary steps in the drop members, with the back of the cross member flush with the back walls of the drop members to maintain the backs of the drop members free of obstructional elements for minimum clearance between the body of the jack and the drop members.

CHARLES L. THOMPSON.

REFERENCES CITED The followingv references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 87,435 Ryan Mar. 2, 1869 1,151,232 Alston et a1. Aug. 24, 1915 FOREIGN PATENTS Number Country Date 4,020 Great Britain Feb. 17, 1912 599,804 France Oct. 26, 1925 

